1. Field of the Invention
The present invention relates to a chip mounting apparatus for sorting and subsequently readily mounting each of a large number of generally square chip components, for example, semiconductor chips, chip capacitors, chip resistors or the like onto a package base or a circuit board.
2. Description of the Prior Art
In general, a large number of semiconductor elements are initially formed into a certain pattern on a semiconductor wafer and are then individually separated into generally square chips. Prior to subsequent die-bonding process, the separated semiconductor chips are successively transported to a chip mounting apparatus, while being bonded on an adhesive expand tape. During the die-bonding process, the semiconductor chips are separated from the expand tape and then picked up one by one by a vacuum pickup collet or the like so as to be mounted on a package base. Alternatively, the chips separated from the tape are occasionally placed on a tray to be rearranged in order.
FIG. 1 depicts a tray 1 to be used for this purpose, which is provided at its upper surface with a plurality of generally square concaves 4 partitioned in regular order generally in the form of a checked pattern by a plurality of partition walls 2 and 3 crossing at right angles. The concaves 4 have the same configuration slightly greater than any chips so that each of the concaves 4 can accommodate any one of the chips regardless of size.
However, when the chips are placed on such a tray 1, they are located at different positions or angles inside respective concaves 4 as a rule, resulting in variations in positional relationship between the chips and the concaves 4 accommodating respective chips. Consequently, the vacuum pickup collet or the like occasionally fails to properly pick up the chips from the tray according to their locations, rendering some of such chips to drop from the collet or to be damaged at their corners. This problem necessitates an image processing system for identifying the position of the chips on the tray 1, which slows each pickup and causes the apparatus to become complicated or to be formed into a relatively large size.